The basis of the invention is to select a pin whose function has some dead time when the pin is not in effective use and using it for another purpose during that time.
In a PWM modulator as might be used in a power converter, a drive signal will be generated on an output pin of an integrated circuit PWM controller device which is used to drive the output when the modulator is required to be on.
In power converter applications it is common to sense the current in the driven circuit, which may be the primary side of an isolation transformer within the converter.